The present invention relates generally to media handling in an imaging device and, more particularly, to a method that adjusts a media positioning sequence based on previous positioning sequences.
In imaging devices such as inkjet and electrophotographic printers, the typical imaging process includes picking a sheet of media from an input tray, feeding the sheet through an imaging zone and then ejecting the sheet through an output port into an output tray. Where faster throughput is desired, a continuous feed or xe2x80x9chead-to-tailxe2x80x9d printing mode may be employed. In head-to-tail printing the printer media handling system picks one media sheet after another to create a series sequence of media sheets that move through the imaging zone and are ejected into the output tray. In this mode the trailing edge of a first media sheet is substantially adjacent to the leading edge of a second media sheet that immediately follows the first sheet. In practice, there is a small gap between the media sheets that is used to discriminate between sheets. An edge detector may be used to sense the leading edge of the second sheet and to position the sheet relative to the imaging zone.
In one method of head-to-tail printing, the ejection of a first or leading sheet and the positioning of the second or trailing sheet may occur in one sequence of movements of the media handling system. In some ejection/positioning sequences the trailing sheet may be positioned too far forward or too far away from its optimal position relative to the imaging zone. Where the second sheet is positioned too far forward, before printing may begin the sheet must first be reversed until the edge detector senses the leading edge. Where the second sheet is positioned too far away from the imaging zone, the sheet must first be advanced before printing may begin. These extra movements of the sheet slow printing throughput and may cause media jams and other media handling errors.
A variety of factors may affect the ejection sequence and the positioning of the trailing sheet relative to the imaging zone. For example, the type of media being printed, the print quality mode selected and environmental conditions may affect the ejection sequence and positioning of the trailing sheet. Additionally, the age of the printer and the wear of printer parts, particularly in the media handling mechanisms, can affect the ejection and positioning of the media sheets.
Some prior imaging devices have utilized two or more fixed ejection sequences that are selected based on various characteristics of the print request, such as the type of media being printed, the length of the media, the print speed required, the print quality, etc. One example of a printer that utilizes different ejection sequences is the DeskJet(copyright) 970 inkjet printer manufactured by Hewlett-Packard Co. of Palo Alto, Calif. This printer selects between a fast and a slow media ejection speed based on the print quality selected by the user (Best, Normal or Draft). The printer may select the slower ejection speed for the Best and Normal settings where printing speed or throughput is less critical to a user, and the faster speed for Draft print jobs where greater throughput is desired. However, these ejection sequences are fixed and cannot adjust to account for the variety of factors that may affect the ejection sequence and the positioning of media sheets.
Thus, a need exists for an improved method for positioning media that addresses the limitations of the prior art.